Variable input control for improving switched power supplies

ABSTRACT

A power converter and a method of operation thereof is disclosed including an input, an output, a sensor unit, a switched power converter, and a processor module. The power converter may convert an input power into an output power. The power converter may sense real-time measurements of the input power and the output power to determine a real-time calculated efficiency. The power converter may chop the input power into sized and positioned portions of the input power based on a plurality of determined operating parameters. The power converter may determine the operating parameters based on the real-time calculated efficiency and on a plurality of other operating factors/conditions.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority from U.S. Provisional PatentApplication No. 61/625,902 filed on Apr. 18, 2012 and from U.S.Provisional Patent Application No. 61/665,766 filed on Jun. 28, 2012,which are incorporated by reference as if fully set forth.

FIELD OF INVENTION

The present invention is related to power conversion.

BACKGROUND

Supplying a clean direct current (DC) power source to electronic devicesin an efficient manner has become increasingly important. Powerconverters are used to take an alternating current (AC) or DC source asan input and generate at its output a clean DC voltage to powerelectronics connected to the power converter. Conventionally, a powerconverter receives as an input an AC voltage and converts it to a DCsupply voltage to power devices such as laptops, desktop computers,computer servers, mobile phones, televisions, home appliances, batterychargers, or any other electrically powered devices requiring a DCvoltage source.

One conventional method for performing such AC to DC power conversionuses linear power supply. Linear power supplies conventionally step downthe AC voltage using a transformer, rectify the stepped-down voltagewith a rectifier bridge, smooth the rectified voltage with an outputcapacitor to generate, and regulate the smoothed output voltage with aregulator. Linear power supplies often suffer from low power conversionefficiency from the input AC power to the output DC power. Furthermore,the necessary size of a transformer for systems operating at a linefrequency of 50 Hz-60 Hz is too large for portable applications and isoften relatively expensive.

A second conventional method for performing AC to DC conversion usesswitch-mode power supplies. Switch-mode power supplies typically have asmaller form-factor than comparable linear power supplies. However,switch-mode power supplies have undesirable non-linear characteristicsthat may introduce harmonics and power factor problems. Furthermore,many switch-mode power supplies may not adapt well to varying operatingfactors/conditions.

Conventional switch-mode power supplies chop a full sine wave input,harvest the associated energy from the chopped input portion, convertand transfer the energy from the chopped input portion to the DC outputstage. The chopping is not dependent on the input waveform, but rather astatic, timed chopping procedure. For instance, conventional powersupplies may be designed to chop a full sine wave input such that allportions of the waveform are chopped at regular intervals, for instanceregularly spaced intervals at a rate of 120,000 times per second, andtransferred to the output regardless of the actual behavior andzero-crossing timing of the input waveform. Alternatively, aconventional power supply may be designed to take portions of the inputequally sized in energy. In this way, the system is designed to takestatically defined, equal in energy portions of the input waveform toproduce the DC output. Such systems are designed to take input portionsat predefined moments wherein a portion taken from a lower voltageregion of the input is wider than a portion taken from a higher voltageregion such that the energy harvested from each portion is equal to theenergy harvested from the other portions. In the constant width portionexample and in the constant energy portion example, portions of an inputvoltage waveform are always taken in the same way and at the samemoments from one period (or half-period) to the next. Furthermore,conventional power converters do not recalibrate based on directmeasurements of efficiency. Conventional power converters performmeasurements to ensure sufficient power is delivered to the outputwithout direct considerations for efficiency. Conventional powerconverters may indirectly monitor and control efficiency by, forinstance, monitoring and controlling an input current. Also,conventional power converters use rectifiers that are inherently lossy.Conventional converters also do not predict a change in future operationbased on current operating factors/conditions and historicallydemonstrated operating factors/conditions.

There is a need for more efficient power conversion. There is a need tomore efficiently harvest and use the input waveform when performingpower conversion than is done in conventional converters. There is aneed to adjust how power is converted based on operatingfactors/conditions and to harvest and use portions of the input based onthese operating factors/conditions. Furthermore, there is a need toselectively use any portions of the entire input sine wave to optimizeoperation and maintain operating conditions within acceptablethresholds. There is also a need to operate at high frequencies, whichallows for the use of smaller components than those used in conventionallinear supplies.

SUMMARY

Disclosed is a method and apparatus for controlling the switching in aswitched power converter according to actual efficiency measured, forexample, in real-time by dividing the output power by the input power ofthe switched power converter. Measuring may be done constantly,periodically, at programmable times, or through any other appropriatemanner. Efficiency may be derived through voltage and current readingsat the input and voltage and current readings at the output.

In accordance with one embodiment, a power converter may sample andcalculate, at high frequency, present real-time voltage values andcurrent values or root-mean-square (RMS) voltage values and RMS currentvalues of an AC input source or a DC input source. At times, the powerconverter may adjust the rate at which it samples and calculatesvoltage, current, RMS, etc. values. The power converter may sample andcalculate present, real-time voltage and current values of a DC output.From these calculations, an actual efficiency of the power converter maybe derived. The power converter may be designed to optimize theefficiency while managing a plurality of other factors/conditions andattempting to maintain operation within acceptable operating limits.

The converter may start with approximate operating parameters based on aDC output voltage and a resistance or current draw of a load. Theconverter may adjust starting and stopping of one or more periods duringwhich the input power may be used for conversion to output power. Thestarting and stopping of one or more periods may be dependent on amultitude of operating factors/conditions, including: power conversionefficiency, harmonics, temperature, expected output voltage, storedenergy level, inductance-based energy storage, storage capacitorvoltage, start-up energy storage levels, output ripple, voltage andcurrent draw of the load, rate of discharge of the storage capacitor,voltage and current of the input power source, frequency of the inputpower source, the rate of change or slope of the input power source, theresonant frequency and a change in the resonant frequency of an LLCconverter, the temperature of the LLC converter, the present positionalong the input A/C waveform, the fluctuation profile of powerconsumption of the load, power factor, information or commands providedby the load or user, over-voltage and/or over-current conditions of theinput and/or output, mechanical noise or vibrations, characteristics ofthe mechanical noise or vibrations, noise profile of the input powersource, electromagnetic interference (EMI), any other factor (orcombination of factors) which may be desirably affected, controlled,adjusted and/or monitored.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the following description,given by way of example in conjunction with the accompanying drawingswherein:

FIG. 1 is a system diagram of a conventional power converter system;

FIG. 2A is a system diagram of an example power converter system inwhich one or more disclosed embodiments may be implemented;

FIG. 2B is a system diagram of another example power converter system inwhich one or more disclosed embodiments may be implemented;

FIG. 3 is an exemplary plot of input current, input voltage, and outputvoltage for a power conversion system;

FIG. 4A is an exemplary diagram of an input source chopped for powerconversion;

FIG. 4B is a exemplary diagram of an input source conventionally choppedfor power conversion;

FIG. 4C is an exemplary diagram of an input source conventionallychopped for power conversion;

FIG. 4D is an exemplary diagram of an input source harvested with burstmode implemented in power conversion;

FIG. 5 is a flow diagram depicting an exemplary process for determiningan order for adjusting operating parameters;

FIG. 6 is a flow diagram depicting another exemplary process fordetermining an order for adjusting operating parameters;

FIG. 7 is a flow diagram depicting an exemplary process for determiningan optimal operating parameter value;

FIG. 8 is a flow diagram depicting an exemplary operating process of anembodiment of a power conversion system;

FIG. 9 is a flow diagram depicting another exemplary operating processof an embodiment of a power conversion system;

FIG. 10 is an exemplary diagram of an input source chopped for powerconversion in various voltage ranges;

FIG. 11 is a circuit diagram of an exemplary embodiment of a powerconversion system; and

FIG. 12 includes two plots of exemplary voltage portions and theresultant partially charged voltage across a capacitor.

DETAILED DESCRIPTION

In one embodiment, a power converter may include an input configured toreceive input power from an input power source, an output configured togenerate a converted power, a sensor unit configured to sense real-timemeasurements of the converted power and the input power, a switchedpower converter configured to chop the input power into portions anddeliver energy harvested from the portions to the output based on aplurality of operating parameters, and a processing module. Theprocessing module may be configured to calculate an efficiency based onthe real-time measurements, determine a position and size of one or moreportions of the input power based on the calculated efficiency, and setthe plurality of operating parameters based on the determined positionand size of the one or more portions of the input power.

In another embodiment, the power converter may include one or moresensors, such as temperature sensors, each configured to sense acondition, such as a temperature of one or more components of the powerconverter.

In another embodiment, the switched power converter may include one ormore switches, wherein the plurality of operating parameters includeparameters to open and close the one or more switches such that the oneor more switches are configured to open and close based on thedetermined position and size of the one or more portions of the inputpower.

In another embodiment, the processing module may be further configuredto determine the position and size of the one or more portions of theinput power based on operating factors/conditions.

In another embodiment, the processing module may be further configuredto determine the position and size of the one or more portions of theinput power based on real-time load requirements.

In another embodiment, the processing module may be further configuredto measure an effect of at least one of the plurality of operatingparameters on the calculated efficiency.

In another embodiment, the processing module may be further configuredto determine an order in which the operating parameters may be set basedon the measured effect of the at least one of the plurality of operatingparameters on the calculated efficiency.

In another embodiment, the order in which the operating parameters areset may be determined to optimize a speed with which the power converterdetermines an optimal efficiency.

In another embodiment, the processing module may be further configuredto determine an order in which the operating parameters may be set basedon an effect of the at least one of the plurality of operatingparameters on at least one operating factor/condition.

In another embodiment, a method for converting power is disclosed. Themethod may include receiving input power from an input power source,generating a converted power at an output, sensing real-timemeasurements of the converted power and the input power, chopping theinput power into portions and delivering the energy harvested from theportions to the output based on a plurality of operating parameters,calculating an efficiency based on the real-time measurements,determining a position and size of one or more portions of the inputpower based on the calculated efficiency, and setting the plurality ofoperating parameters based on the determined position and size of theone or more portions of the input power.

In another embodiment, a method for converting power may include sensinga condition, such as a temperature of one or more components of thepower converter.

In another embodiment, a method for converting power may include openingand closing one or more switches based upon the plurality of operatingparameters such that the one or more switches are opened and closedbased on the determined position and size of the one or more portions ofthe input power.

In another embodiment, a method for converting power may includedetermining the position and size of the one or more portions of theinput power based on operating factors/conditions.

In another embodiment, a method for converting power may includedetermining the position and size of the one or more portions of theinput power based on real-time load requirements.

In another embodiment, a method for converting power may includemeasuring an effect of at least one of the plurality of operatingparameters on the calculated efficiency.

In another embodiment, a method for converting power may includedetermining an order in which the plurality of operating parameters areset based on the measured effect of the at least one of the plurality ofoperating parameters on the calculated efficiency.

In another embodiment, a method for converting power may includedetermining the order in which the plurality of operating parameters areset to optimize a speed with which the power converter determines anoptimal efficiency.

In another embodiment, a method for converting power may includedetermining an order in which the plurality of operating parameters areset based on an effect of at least one of the plurality of operatingparameters on at least one operating factor/condition.

In another embodiment, a power converter may include an input configuredto receive an input power waveform from an input power source, an outputconfigured to generate a converted power, a sensor unit configured tosense at least one indication of an operating condition, and a switchedpower converter configured to select one or more portions of the inputpower waveform based on the at least one indication of an operatingcondition and convert the one or more portions of the input powerwaveform to the output.

In another embodiment, the switched power converter may be furtherconfigured to convert the one or more portions of the input powerwaveform to the output based on the at least one indication of anoperating condition.

In another embodiment, the switched power converter may be furtherconfigured to charge at least one energy storage device based on the atleast one indication of an operating condition.

In another embodiment, the switched power converter may be furtherconfigured to select one or more portions of the input power waveform tosatisfy a target operating condition.

In another embodiment, the switched power converter may be furtherconfigured to avoid selecting one or more portions of the input powerwaveform to satisfy the target operating condition.

In another embodiment, the sensor unit may be further configured tosense a change in the at least one indication of an operating condition.Furthermore, the switched power converter may be further configured toselect one or more different portions of the input power waveformresponsive to the sensed change in the at least one indication of anoperating condition.

In another embodiment, the power converter may include a processingmodule configured to determine a position and size of the one or moreportions of the input power waveform, and set a plurality of operatingparameters based on the determined position and size of the one or moreportions of the input power waveform. Furthermore, the switched powerconverter may be further configured to select the one or more portionsof the input power waveform based on the plurality of operatingparameters.

In another embodiment, the processing module may be further configuredto calculate an efficiency based on real-time measurements of the inputpower waveform and the converted power, and set the plurality ofoperating parameters based on the real-time measurements.

In another embodiment, the switched power converter may be furtherconfigured to harvest energy of the one or more portions of the inputpower waveform and deliver the harvested energy of the one or moreportions of the input power waveform to the output.

In another embodiment, a method is disclosed for converting power in apower converter, which may include receiving an input power waveformfrom an input power source, generating a converted power at an output,sensing at least one indication of an operating condition, selecting oneor more portions of the input power waveform based on the at least oneindication of an operating condition, and converting the one or moreportions of the input power waveform to the output.

In another embodiment, a method for converting power may includeconverting the one or more portions of the input power waveform to theoutput based on the at least one indication of an operating condition.

In another embodiment, a method for converting power may includecharging at least one energy storage device based on the at least oneindication of an operating condition.

In another embodiment, a method for converting power may includeselecting one or more portions of the input power waveform to satisfy atarget operating condition.

In another embodiment, a method for converting power may includeavoiding selecting one or more portions of the input power waveform tosatisfy the target operating condition.

In another embodiment, a method for converting power may include sensinga change in the at least one indication of an operating condition, andwherein the switched power converter is further configured to select oneor more different portions of the input power waveform responsive to thesensed change in the at least one indication of an operating condition.

In another embodiment, a method for converting power may includedetermining a position and size of the one or more portions of the inputpower waveform, setting a plurality of operating parameters based on thedetermined position and size of the one or more portions of the inputpower waveform, and selecting the one or more portions of the inputpower waveform based on the plurality of operating parameters.

In another embodiment, a method for converting power may includecalculating an efficiency based on real-time measurements of the inputpower waveform and the converted power, and setting the plurality ofoperating parameters based on the real-time measurements.

In another embodiment, a method for converting power may includeharvesting energy of the one or more portions of the input powerwaveform, and delivering the harvested energy of the one or moreportions of the input power waveform to the output.

In another embodiment, a power converter may include an input configuredto receive an input power waveform from an input power source, aswitched power converter configured to harvest energy from one or moreportions of the input power waveform, wherein the harvested energy ofthe one or more portions is substantially less than the available energyof the input power waveform, an energy storage device, and an outputstage. The output stage may be configured to receive the harvestedenergy, convert the harvested energy into a converted energy, and storethe converted energy in the energy storage device.

In another embodiment, the switched power converter may be furtherconfigured to select a location of a first portion of the one or moreportions of the input power waveform, and select a location of a secondportion of the one or more portions of the input power waveform, whereinthe location of the first portion may be substantially separated in timefrom the location of the second portion such that the first portion maynot be adjacent to the second portion.

In another embodiment, the input power waveform may be an alternatingcurrent (AC) input power waveform.

In another embodiment, the switched power converter may be furtherconfigured to selected locations of the one or more portions such thatthe one or more portions may be positioned along the same half-wave ofthe AC input power waveform.

In another embodiment, no portions of the AC input power waveform may beselected at a position between the first portion and the second portion.

In another embodiment, the first portion may be positioned prior to apeak of the half-wave and the second portion may be positioned after thepeak of the half-wave.

In another embodiment, both the first portion and the second portion maybe positioned on the same side of the peak of the half-wave.

In another embodiment, the location of the first portion may include awidth of the first portion and the location of the second portion mayinclude a width of the second portion. Furthermore, the switched powerconverted may be further configured to select the width of the firstportion and the width of the second portion, wherein the width of thefirst portion may be different than the width of the second portion.

In another embodiment, the switched power converter may be furtherconfigured to select locations of the one or more portions of the inputpower waveform such that the one or more portions may be inhomogeneouslypositioned along the input power waveform and the one or more portionsmay be inhomogeneously sized.

In another embodiment, the output stage may be further configured tosupply a substantially direct current (DC) voltage to a load device.

In another embodiment, a method for converting power in a powerconverter may include receiving an input power waveform from an inputpower source, harvesting energy from one or more portions of the inputpower waveform, wherein the harvested energy of the one or more portionsmay be substantially less than the available energy of the input powerwaveform, converting the harvested energy into a converted energy, andstoring the converted energy in an energy storage device.

In another embodiment, a method for converting power in a powerconverter may include selecting a location of a first portion of the oneor more portions of the input power waveform, and selecting a locationof a second portion of the one or more portions of the input powerwaveform, wherein the location of the first portion may be substantiallyseparated in time from the location of the second portion such that thefirst portion may not be adjacent to the second portion.

In another embodiment, a method for converting power in a powerconverter may include selecting locations of the one or more portionssuch that the one or more portions may be positioned along the samehalf-wave of the AC input power waveform.

In another embodiment, a method for converting power in a powerconverter may include the input power waveform being an alternatingcurrent (AC) input power waveform.

In another embodiment, a method for converting power in a powerconverter may include no portions of the AC input power waveform beingselected at a position between the first portion and the second portion.

In another embodiment, a method for converting power in a powerconverter may include the first portion being positioned prior to a peakof the half-wave and the second portion being positioned after the peakof the half-wave.

In another embodiment, a method for converting power in a powerconverter may include both the first portion and the second portionbeing positioned on the same side of the peak of the half-wave.

In another embodiment, a method for converting power in a powerconverter may include the location of the first portion including awidth of the first portion and the location of the second portionincluding a width of the second portion. The method may further includeselecting the width of the first portion and the width of the secondportion, wherein the width of the first portion may be different thanthe width of the second portion.

In another embodiment, a method for converting power in a powerconverter may include selecting locations of the one or more portions ofthe input power waveform such that the one or more portions may beinhomogeneously positioned along the input power waveform and the one ormore portions may be inhomogeneously sized.

In another embodiment, a method for converting power in a powerconverter may include supplying a substantially direct current (DC)voltage to a load device.

In another embodiment, a power converter may include an input configuredto receive an alternating current (AC) input power waveform from aninput power source, a switched power converter, and an output stage. Theswitched power converter may be configured to harvest power from one ormore portions of a first half-wave of the AC input power waveform, andharvest power from one or more portions of a second half-wave of the ACinput power waveform, wherein at least one location of at least one ofthe one or more portions of the first half-wave may be different than atleast one location of at least one of the one or more portions of thesecond half-wave. The output stage may be configured to receive theharvested power, and convert the harvested power into a converted power.

In another embodiment, the power converter may include an energy storagedevice configured to store the converted power.

In another embodiment, the power converter may include a processingmodule configured to select the locations of the one or more portions ofthe first half-wave, select the locations of the one or more portions ofthe second half-wave, and send control signals to the switched powerconverter based on the selected locations of the one or more portions ofthe first-half wave and based on the selected locations of the one ormore portions of the second-half wave.

In another embodiment, the processing module may be further configuredto determine one or more settings for the output stage, and send one ormore control signals to the output stage based on the determined one ormore settings.

In another embodiment, the switched power converter may be furtherconfigured to harvest power from a plurality of consecutive half-wavesof the AC input power waveform such that different portions of the powermay be harvested from each half-wave of the plurality of consecutivehalf-waves of the AC input power waveform.

In another embodiment, each of the locations of the portions may includea position and a width. Furthermore, the processing module may befurther configured to select a width of a portion of the firsthalf-wave, and select a width of a portion of the second half-wave, suchthat the width of the portion of the second half-wave may be wider thanthe width of the portion of the first half-wave.

In another embodiment, the processing module may be configured to selecta different number of portions of the first half-wave than number ofportions of the second half-wave.

In another embodiment, the processing module may be configured to selecta location of a first portion of the one or more portions of the firsthalf-wave, and select a location of a second portion of the one or moreportions of the first half-wave, wherein the locations of the firstportion and the second portion may be such that a gap exists between thefirst portion and the second portion in which no other portion exists.

In another embodiment, the processing module may be configured to adjustthe locations of the first portion and the second portion such thatcorresponding portions of the second half-wave may be a differentdistance apart than in the first half-wave.

In another embodiment, the processing module may be configured to adjusta width of a first portion of the one or more portions of the firsthalf-wave such that a width of a corresponding portion of the secondhalf-wave may be different than in the first half-wave.

In another embodiment, a method for converting power in a powerconverter may include receiving an alternating current (AC) input powerwaveform from an input power source, harvesting power from one or moreportions of a first half-wave of the AC input power waveform, harvestingpower from one or more portions of a second half-wave of the AC inputpower waveform, and converting the harvested power into a convertedpower, wherein at least one location of at least one of the one or moreportions of the first half-wave may be different than at least onelocation of at least one of the one or more portions of the secondhalf-wave.

In another embodiment, a method for converting power in a powerconverter may include storing the converted power in an energy storagedevice.

In another embodiment, a method for converting power in a powerconverter may include selecting the locations of the one or moreportions of the first half-wave, selecting the locations of the one ormore portions of the second half-wave, and sending control signals tocontrol the harvesting based on the selected locations of the one ormore portions of the first-half wave and based on the selected locationsof the one or more portions of the second-half wave.

In another embodiment, a method for converting power in a powerconverter may include determining one or more settings for an outputstage, and sending one or more control signals to the output stage basedon the determined one or more settings.

In another embodiment, a method for converting power in a powerconverter may include harvesting power from a plurality of consecutivehalf-waves of the AC input power waveform such that different portionsof the power may be harvested from each half-wave of the plurality ofconsecutive half-waves of the AC input power waveform.

In another embodiment, a method for converting power in a powerconverter may include each of the locations of the portions including aposition and a width. The method may further include selecting a widthof a portion of the first half-wave, and selecting a width of a portionof the second half-wave, such that the width of the portion of thesecond half-wave may be wider than the width of the portion of the firsthalf-wave.

In another embodiment, a method for converting power in a powerconverter may include selecting a different number of portions of thefirst half-wave than number of portions of the second half-wave.

In another embodiment, a method for converting power in a powerconverter may include selecting a location of a first portion of the oneor more portions of the first half-wave, and selecting a location of asecond portion of the one or more portions of the first half-wave,wherein the locations of the first portion and the second portion may besuch that a gap exists between the first portion and the second portionin which no other portion exists.

In another embodiment, a method for converting power in a powerconverter may include adjusting the locations of the first portion andthe second portion such that corresponding portions of the secondhalf-wave may be a different distance apart than in the first half-wave.

In another embodiment, a method for converting power in a powerconverter may include adjusting a width of a first portion of the one ormore portions of the first half-wave such that a width of acorresponding portion of the second half-wave may be different than inthe first half-wave.

FIG. 1 depicts a traditional architecture for a power conversion system.System 100 may receive input power from an input power source 110 whichmay be an alternating current (AC) or direct current (DC) voltage orcurrent source. The input power from the input power source 110 may thenbe operated on by a power converter 120 to convert the input power to anappropriate output voltage for a load device 130. Power converter 120may include one or more rectifiers, switches, energy storage devices,transformers, transistors, diodes, and/or other traditional electricalelements used in traditional power converters. Power converter 120 maybe designed to control at least one switch to chop the input powersource 110 so that regularly defined portions of the input waveform areused to produce a DC voltage at the output. The at least one switch maybe used to chop the input waveform at regular intervals in time, or suchthat the area of each chopped portion is equal, and the drawn inputcurrent is varied such that a substantially constant correspondingenergy from the input power source 110 is passed through the powerconverter 120 to produce an output voltage to power the load device 130.

In an exemplary embodiment of an improved power conversion system forconverting power from an input power source to a load, the system maycomprise analog or digital controls for charging a storage capacitor tofeed energy to the load. The system may not be restricted to charging astorage capacitor and may alternatively or additionally store energy inany energy storage device such as an inductor, a battery, a supercapacitor, or any other energy storage mechanism. The power conversionsystem may control powering the load such that energy may be fed fromthe input power source to the load, energy may be fed from the inputpower source to the storage device, the energy stored in the storagedevice may be fed to the load, or any combination thereof. As anadditional example, the power conversion system may simultaneously powerthe load and the storage capacitor. In another embodiment, the powerconversion system may disconnect any of the input power source, storagecapacitor, or load from each other. Please see PCT publication WO2012-014202 for further details.

FIG. 2A depicts an exemplary embodiment of a high-efficiency powerconversion system 200. The power conversion system 200 may include aninput power source 210. The input power source 210 may be an AC or DCpower source. The input power source 210 may be coupled to a switchedpower converter 220. The switched power converter 220 may then feed a DCpower-out stage 240. The DC power-out stage 240 may be viewed as anoutput power stage including an energy storage device 241. FIG. 2Adepicts the energy storage device 241 as a capacitor. Alternatively, theenergy storage device 241 could be a plurality of capacitors or anotherenergy storage device such as an inductor, battery, super capacitor, anyother energy storage mechanism, or any combination thereof. The load 230may be coupled to the DC power-out stage 240.

The power conversion system 200 may further include a subsystem 250which may sense or detect operating factors/conditions and may performlogic and controls for evaluating operating factors/conditions to adjustand control the switched power converter 220 to affect the overallefficiency of the power conversion process while attempting to keep thesystem operating within acceptable operating condition thresholds.Subsystem 250 may receive input 211 from the input power source 210.Subsystem 250 may receive input 222 from the switched power converter220. Subsystem 250 may receive input 242 from the DC power-out stage240. Subsystem 250 may receive input 231 from the load 230. Subsystem250 may monitor any combination of inputs 211, 222, 242, and 231 totrack operating factors/conditions and to adjust and control powerconversion based on the operating factors/conditions.

Subsystem 250 may include a processor for processing the incomingsignals/inputs and for performing logic and operations to control theoperation of the power conversion system 200. The subsystem 250 mayadjust or control parameters through signaling 221 to determine thestarting and stopping of the switches of the switched power converter220. The processor may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Array (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor may perform signal coding, data processing,power control, input/output processing, and/or any other functionalitythat enables the power conversion system 200 to control the conversionof input power to output power. The processor may be coupled to inputs,outputs, sensors, memory, and any other logical connections fordetermining the operating factors/conditions of the system 200 and forcontrolling the system in real-time.

The switched power converter 220 may be controlled to chop an inputwaveform of the input power source 210 into selected portions. Choppingmay be considered any method by which the switched power converter 220selects and harvests a portion of the input power. Chopping may beeffected by switches turning on and off to selectively allow the inputof power from the input power source 220. Chopping may be effected bycontrolling an input resistance and raising or lowering the inputresistance appropriately to control the input of power from the inputpower source 220. Chopping may be accomplished by any apparatus,mechanism, or methodology by which the switched power converter 220 mayselect and harvest energy from the input and direct the energy forconversion to the DC power-out stage 240 to be ultimately delivered tothe load 230. Chopping may be accomplished by any method or apparatusfor chopping an input waveform into portions of the waveform. No formaldefinitions or limitations are implied by the use of the term“chopping.” One of ordinary skill in the art should recognize choppingto be a generic form of selectively harvesting portions of an inputpower from the input power source 210.

FIG. 2B depicts another exemplary embodiment of a high-efficiency powerconversion system. The high-efficiency power conversion system mayinclude an EMI filter and input protection block connected to an inputpower source. The system may further include an AC rectifier coupled tothe EMI filter and input protection block. The system may furtherinclude an AC-DC converter with power factor correction (PFC) coupled tothe AC rectifier. The system may further include a DC-DC convertercoupled to the AC-DC converter. The DC-DC converter may include an LLCconverter and may be coupled to a load. The system may further include acontroller subsystem. The controller subsystem may include an ACpolarity sensor which may be coupled to and sense the output of the EMIfilter and input protection block. The AC polarity sensor may be coupledto, and output a digital signal to, a supervisory digital controller.The supervisory digital controller may receive signals from sensorswhich may sense operating factors/conditions of the outputs and inputsbetween the AC rectifier, AC-DC converter, DC-DC converter, and load.The signals from sensors may further include indications of operatingfactors/conditions such as voltages and currents. As shown in theexemplary embodiment of FIG. 2B, the supervisory digital controller maysense the voltage between the AC-DC converter stage and the DC-DCconverter stage, and may also sense both the current and voltage outputfrom the DC-DC converter stage. The supervisory digital controller mayalso receive thermal indications or signaling from the AC-DC converterand from the DC-DC converter. The supervisory digital controller maysend control signals, which may be in the form of settings or ofadjustments of operating parameters, to the EMI filter and inputprotection stage, to the AC rectifier, to a PFC controller, and/or to aDC-DC controller. The PFC controller may be coupled to and send controlsignals to the AC-DC converter. The PFC controller may control the AC-DCconverter based on signals received from the supervisory digitalcontroller. The PFC controller may also send feedback signals to thesupervisory digital controller. The PFC controller may also sense andreceive signaling from the output of the EMI filter and input protectionstage. The DC-DC controller may be coupled to and send control signalsto the DC-DC converter. The DC-DC controller may control the DC-DCconverter based on signals received from the supervisory digitalcontroller. The DC-DC controller may also send feedback signals to thesupervisory digital controller. In this way, the exemplary system ofFIG. 2B may monitor operating factors/conditions by receivingindications of the operating factors/conditions from sensors and may setoperating parameters through control signals to control the selection ofportions of the input waveform and the energy contained in the portions;it may control the conversion of the energy of the selected portions;and it may control the delivery of the converted energy to a storagedevice or to the load. Though the connections, sensor signals, controlsignals, and arrangements of components illustrated in FIG. 2B depict aparticular embodiment, one skilled in the art should recognize variousadditional signals, connections, and arrangements may be possible.Furthermore, fewer signaling or control connections may be possible.

In another embodiment, a method of controlling the switching in aswitched power converter is further disclosed according to actualefficiency measured, for example, in real-time by dividing the outputpower by the input power of the switched power converter. The inputpower and output power may be measured constantly, periodically,sampled, at particular predefined times, during particular portions ofan AC period corresponding to a particular voltage, or any combinationthereof. The method may include sampling and calculating, at highfrequency and in real-time, present real-time voltage and current of anAC or DC input. Alternatively, the frequency at which the sampling andcalculating of the input may be done may be adjusted higher or to lowerfrequencies. For example, for a 120V AC input, the present voltage mayvary from −120V nominally through 0V to +120V nominally through a periodof the AC sinusoid. The method may further comprise sampling andcalculating, at high frequency and in real-time, a present voltage andcurrent of a DC output. Alternatively, the frequency at which thesampling and calculating of the output may be done may be adjustedhigher or to lower frequencies. From these calculations, the actualefficiency of the power converter may be derived.

When the system is starting up, power may be fed to a start-up processoror other controlling module of the power conversion system. The powermay be fed through a start-up power supply that may comprise arectifier, a small capacitor, a battery, or any other power supplydesigned for start-up. Power may be supplied to wake up the start-upprocessor. Once the start-up processor is awake, the start-up processormay sample input source characteristics, input parameters, or any otheroperating factors/conditions. The input parameters may be provided by auser, provided by the load, or may be programmed into the system. Thestart-up processor may be implemented by a simple processor, discreteelectronics, analog circuitry, any other computational device orcontroller, or any combination thereof.

The start-up processor may then access memory, a look-up table,dip-switches, previously stored data, or any other preprogrammed methodor device to retrieve initial values for operating parameters. Thestart-up processor may then update the system according to the initialoperating parameters. The initial operating parameters may be used toestablish initial operating conditions including an initial operatingoutput level. The start-up processor may further verify whether otheroperating factors/conditions are within an acceptable range. Suchfactors/conditions may include: power conversion efficiency, harmonics,temperature, expected output voltage, stored energy level,inductance-based energy storage, storage capacitor voltage, start-upenergy storage levels, output ripple, voltage and current draw of theload, rate of discharge of the storage capacitor, voltage and current ofthe input power source, frequency of the input power source, the rate ofchange or slope of the input power source, the resonant frequency and achange in the resonant frequency of an LLC converter, the temperature ofthe LLC converter, the present position along the input A/C waveform,the fluctuation profile of power consumption of the load, power factor,information or commands provided by the load or user, over-voltageand/or over-current conditions of the input power source and/or output,mechanical noise or vibrations, characteristics of the mechanical noiseor vibrations, noise profile of the input, electromagnetic interference(EMI), any other factor which may be desirably affected, controlled,adjusted and/or monitored, and any combination thereof.

The start-up processor may wake-up a main controller or other suitablecomputational device and verify whether the main controller is workingproperly. In one embodiment, the start-up processor may verify whetherthe main controller is working properly by verifying the output voltageon the storage capacitor is within an acceptable range. As mentionedpreviously and throughout this disclosure, an alternative storage devicemay be used and the start-up processor may verify that an associatedenergy level of the storage device is within an acceptable range. Toverify the output voltage on the storage capacitor, several samples maybe taken. Once the main controller has been verified to be workingproperly, the start-up processor and its start-up power supply may entera sleep mode. In one embodiment, the start-up power supply may be asimple power supply. In another embodiment, the system may be designedand configured to allow initial charging of any energy storage device ordevices. The energy storage devices may then be used to start up themain controller. In this way, the system may be implemented without astart-up processor.

FIG. 3 depicts an exemplary plot of an input voltage 310 and inputcurrent 320 for an embodiment of a power conversion system. The inputvoltage 310 has been rectified and the input current 320 is associatedwith the current demands of a load and the input voltage 310. FIG. 3further depicts an exemplary plot of an output voltage 330 correspondingto the input voltage 310 and input current 320. The output voltage 330exhibits ripple 340 in a region of the output 350 due to the low inputenergy regions of the input voltage 310 near the zero-crossing.

The power conversion system may initially approximate and set operatingparameters based on the DC output voltage and the resistance or currentdraw of the load. The operating parameters may control the state of theswitches of the switched power converter to appropriately take portionsof the input power for conversion to output power. The control of theswitches may also influence and control the manner in which power isconverted from input to output. In this way, the control of the switchesmay select the portions of the input power to harvest and may controlhow the input power is converted, stored, and delivered to the load. Thepower conversion system may adjust starting and stopping of one or moreperiods during which the input power is used for conversion to theoutput. The starting and stopping may be dependent on a multitude offactors, including: power conversion efficiency, harmonics, temperature,expected output voltage, stored energy level, inductance-based energystorage, storage capacitor voltage, start-up energy storage levels,output ripple, voltage and current draw of the load, rate of dischargeof the storage capacitor, voltage and current of the input power source,frequency of the input power source, the rate of change or slope of theinput power source, the resonant frequency and a change in the resonantfrequency of an LLC converter, the temperature of the LLC converter, thepresent position along the input A/C waveform, the fluctuation profileof power consumption of the load, power factor, information or commandsprovided by the load or user, over-voltage and/or over-currentconditions of the input power source and/or output, mechanical noise orvibrations, characteristics of the mechanical noise or vibrations, noiseprofile of the input, electromagnetic interference (EMI), any otherfactor which may be desirably affected, controlled, adjusted and/ormonitored, and any combination thereof.

An exemplary power conversion system sets or adjusts operatingparameters to control the power conversion process. In one embodiment,the operating parameters may be viewed as any controls that influencethe switching of the switched power converter. For instance, operatingparameters may be voltage levels, current levels, power levels, energylevels, stored digital or analog values, switch positions, or any othercontrollable parameter, level, or value through which the system mayinfluence the switching of the switched power converter. By setting oradjusting operating parameters, the system may control the switching ofthe switched power converter to appropriately take portions of the inputand appropriately convert the input portions to output power to optimizeoperation. An optimal operation may include maximizing power conversionefficiency while maintaining operating factors/conditions withinacceptable respective thresholds.

In one embodiment, the system may control switching such that a switchcontrols the input of power from an input power source to optimizeperformance such that power conversion efficiency is optimized whilemanaging operating parameters to maintain other operatingfactors/conditions within acceptable levels. The system may takeportions of input power one or more times per a particular period tofind an optimal operating state. For instance, for an AC input, thesystem may start to take power from the input when the input reaches afirst level of present input voltage, and may stop taking power when theinput voltage reaches a second level of present input voltage, whereinthe occasions where the system starts and stops are recalibrated tooptimize some or all operating factors/conditions. In anotherembodiment, the system may override previously determined operatingparameters based on other operating factors/conditions, such as the loadchanging, the load being disconnected, the power consumption of theload, or any fault condition on the input or output. A fault conditionmay be any over/under-temperature, over/under-voltage,over/under-current, ripple, or other operating factors/conditionsoutside of established thresholds.

In another embodiment, the system may include circuitry to convert aninput power to an output power. The circuitry may take a portion of theinput power and convert it to be stored in an energy storage device ordirected to a load device based on a power profile. The circuitry maychop an input source to take a portion of the input and direct theenergy of the portion to one or more energy storage devices. Forexample, the circuitry may be controlled by operating parameters and mayadjust switching such that a narrower portion is selected from the inputto be converted and delivered to an energy storage device.Alternatively, the circuitry may further take a portion of an inputportion to effectively select a narrower portion and convert and deliverthe narrower portion to an energy storage device. The power profile maybe used to control the charging and discharging of the energy storagedevices to convert input power into output power. The system may takeportions of any input power, for instance AC, DC or any waveform, andconvert the portions of the input into an output waveform.

The system may input a portion of the input power, wherein the portionmay be described as having a starting point and an ending point, andfurther wherein these points may be determined based on the operatingfactors/conditions. The starting and ending points may be characterizedby a voltage level, a current level, a power level, an absolute time, arelative time, a time relative to a zero-crossing, or othercharacteristics. The portion may be characterized as having a startingpoint and a width. The portion may be characterized as having a startingpoint and a duration. A portion may be characterized as providing aparticular amount of energy. The portion may be characterized as havinga starting point that is an offset or delay from a prior event. Theprior event may be a zero-crossing of an AC input or detection thereof.The prior event may be the ending point, center point, starting point,or any other point of a prior portion or detection thereof. The pointsof a portion may describe an associated absolute or relative phase of aninput waveform or may describe an associated absolute or relative levelof an input waveform.

Through finding optimal operating parameters, the system may takemultiple portions during a given period. For instance, for an AC input,the system may take multiple portions in a half cycle of an AC period.Each portion may have a starting point and stopping point that may bedetermined based on operating factors/conditions to optimize performanceof the system. Each portion may be characterized by determined positions(possibly a center position of the portion), starts, stops, widths,offsets, and delays. A portion may be characterized by a location alongan input waveform. The location may include any combination of aposition, a start, a stop, a width, an offset, a delay, a duration, etc.Operating parameters may be set to adjust the positions, starts, stops,widths, offsets, delays, etc. of the portions.

Each portion may be made up of further portions. In one embodiment, aportion may comprise multiple further portions, wherein each furtherportion may have determined characteristics such as positions, starts,stops, widths, delays, etc. In this way, a portion may be viewed ascomprising narrower portions with determined characteristics similarlyas characteristics are determined for any other portion. Any portion maybe further made up of even narrower portions of increased resolution. Assuch, a first portion may be characterized as being made up of ahomogeneous or inhomogeneous collection of determined further portionsand each further portion may also comprise determined even furtherportions, and so on. In this way, a portion at a particular level ofresolution may be characterized as having a duty cycle. Therefore, thesystem may set operating parameters to chop up an AC or DC input powerin any pattern which may be determined to optimize performance. Forexample, portions may be determined and characterized by theirpositions, starting points, stopping points, delays, widths, etc. suchthat the portions may be regularly or irregularly spaced. In anotherexample, the system may set operating parameters to take no portions ofthe input for one or more cycles or for a duration of time. The systemmay decide to use the full duty cycle of the input power for a period oftime. The system may be flexible to chop up the input power to take theportions of the input power that result in the most efficient powerconversion process while also taking into considerations any otheroperating factors/conditions as described previously. For instance, thesystem may chop up the input so that an output voltage is reliably andefficiently maintained while keeping harmonics generation, heat, ripple,and noise within acceptable levels.

FIG. 4A depicts an example of an input being chopped by the system foruse in power conversion. As shown in FIG. 4A, portion 410 may becharacterized by a start time 411 and an end time 412. Start time 411may correspond to a real-time starting voltage 413 and end time 412 maycorrespond to a real-time ending voltage 414. Portion 410 mayalternatively or additionally be characterized by voltages 413 and 414.Portion 420 may be characterized by a position 421 and a duration 422 orby an average voltage 423, or it may alternatively or additionally becharacterized by a delay 425 from a prior portion. Portion 430 may becharacterized by an offset 431 from a prior event, for example from azero-crossing as shown in FIG. 4A. Further, portion 430 may be furthercharacterized by a width 432. A portion 440 may be made up of furtherportions 441, 442, 443, and 444. As explained above, the portions andthe space between the portions may be homogenous or inhomogeneous.Portion 450 may also be made up of further portions, wherein portion 450may have a different duty cycle than portion 440. The duty cycle ofportion 450 may be characterized by the width of the portions 451, 453,455 vs. the width of the gaps 452 and 454. Though FIG. 4A depictsseveral portions characterized in different exemplary manners, oneshould recognize any combination of characteristics may be used todefine or characterize portions.

In contrast, FIGS. 4B and 4C illustrate two different types ofconventionally chopped inputs of conventional converters. FIG. 4Billustrates a first conventionally chopped input voltage waveform. Inthis example, an associated switched power converter may be designed tochop the input such that each portion is substantially adjacent to thenext portion such that substantially no gap exists between the portions,and all portion widths are equal. In practice, the switching timenecessary to operate in the conventional power converter will generate asmall gap. However, the system is not designed to implement a gap. It ismerely a function of the finite switching time of the switches withwhich the conventional power converter harvests energy. Furthermore, theinput is chopped such that all portions are the same from one period tothe next across all periods. This can be seen by the first half-cycle ofthe waveform being chopped in the same manner as the second half-cycleof the waveform. One of ordinary skill in the art would recognize thiswould continue in a similar fashion for future sinusoidal periods of thewaveform. In this way, the first conventional switched power converterharvests statically predetermined portions across the full AC waveformacross all periods. In practical, conventional switched powerconverters, energy is not harvested from very low voltage portions ofthe waveform due to hardware limitations and available energy, however,the systems are still considered to be designed to harvest across allfull half-waves of the AC waveform.

FIG. 4C illustrates a second conventionally chopped input voltagewaveform. In this example, an associated switched power converter may bedesigned to chop the input such that each portion is substantiallyadjacent to the next portion such that no gap exists between theportions, and all portions occupy a substantially similar area under thecurve. In practice, the switching time necessary to operate in theconventional power converter will generate a small gap. However, thesystem is not designed to implement a gap. It is merely a function ofthe finite switching time of the switches with which the conventionalpower converter harvests energy. In this way, the current drawn from theinput may have a smaller difference from most current draw to leastcurrent draw for each portion by virtue of the widths of the portionsincreasing for lower voltages. The input voltage is chopped such thateach half-cycle of the waveform is chopped in the same manner as anyprevious and subsequent half-wave. This can be seen by the firsthalf-wave being chopped in the same manner as the second half-cycle ofthe waveform. One of ordinary skill in the art would recognize thiswould continue in a similar fashion for future sinusoidal periods of thewaveform. In this way, the second conventional switched power converterharvests statically predetermined portions across the full AC waveformacross all periods. In practical, conventional switched powerconverters, energy is not harvested from very low voltage portions ofthe waveform due to hardware limitations and available energy, however,the systems are still considered to be designed to harvest across allfull half-waves of the AC waveform.

FIG. 4D illustrates burst mode operation in conventional powerconverters. Burst mode is a feature which may be incorporated intoconventional power converters chopping input waveforms in the mannerillustrated in FIG. 4B and FIG. 4C. Burst mode allows a power converterto stop harvesting energy from the input at any point in time once ithas been determined that a sufficient energy has been stored in anenergy storage device. Conventionally a power converter that is burstmode capable may stop harvesting energy from the input when a load isconnected to the power converter which does not draw a great deal ofpower, enabling the power converter to cease harvesting energy from theinput. Burst mode does not take into consideration changing operatingfactors/conditions but merely ceases energy harvesting when it isdetermined an energy storage device is sufficiently charged for theload. Once the load drains the energy storage device beyond a particularthreshold, the power converter may restart harvesting of energy from theinput at the next zero-crossing of the input waveform.

FIG. 4A illustrates a more flexible method and capability to chop theinput for use in power conversion than that of FIG. 4B and FIG. 4C incombination or not with the burst mode capability illustrated in FIG.4D. The system associated with FIG. 4A may be configured to chop anydetermined portion of the input waveform for use in power conversion.Exemplary gaps 425, 431, 452, and 454 in the chopping and harvesting ofinput waveform are seen. FIG. 4 clearly illustrates further unlabeledgaps before, after, and between harvested portions of the inputwaveform. In contrast, the waveforms of FIG. 4B and FIG. 4C have no gapsbetween portions. In this way, the full half-cycles of the waveforms ofFIG. 4B and FIG. 4C are harvested. Furthermore, in FIG. 4A, the portionsdetermined for harvesting in the first half-cycle of the waveform aredifferent than those of the second half-cycle. In this way, the powerconversion system corresponding to FIG. 4A may flexibly and determineportions of the input waveform to harvest and flexibly determineportions of the waveform to not harvest. This system may make thesedeterminations in real-time and on the fly. This system may determineportions for harvesting and for avoiding based on present and changingoperating factors/conditions. In contrast, the systems corresponding toFIGS. 4B and 4C perform statically determined switching wherein thesystems are designed to perform switching at substantially the sameposition along the input waveform and across all periods. The systems ofFIG. 4B and FIG. 4C lack the flexibility to choose the most preferredportions of the input for use in power conversion dependent on designpreferences, operating parameters, operating factors/conditions, etc.that is implementable by the system corresponding to FIG. 4A.

In one embodiment of a power conversion system in accordance with theteachings herein, an energy storage device, such as a storage capacitor,may be charged in accordance with operating parameters and the voltageof the storage capacitor may be an operating factor/condition. Thestorage capacitor may be charged during one or more charging periodswherein the start and end of the one or more charging periods isdetermined based on the operating parameters. Operating parameters mayalso change during operation. Operating factors/conditions which mayinfluence the operating parameters may include power conversionefficiency, harmonics, temperature, expected output voltage, storedenergy level, inductance-based energy storage, storage capacitorvoltage, start-up energy storage levels, output ripple, voltage andcurrent draw of the load, rate of discharge of the storage capacitor,voltage and current of the input power source, frequency of the inputpower source, the rate of change or slope of the input power source, theresonant frequency and a change in the resonant frequency of an LLCconverter, the temperature of the LLC converter, the present positionalong the input A/C waveform, the fluctuation profile of powerconsumption of the load, power factor, information or commands providedby the load or user, over-voltage and/or over-current conditions of theinput power source and/or output, mechanical noise or vibrations,characteristics of the mechanical noise or vibrations, noise profile ofthe input, electromagnetic interference (EMI), any other factor whichmay be desirably affected, controlled, adjusted and/or monitored, andany combination thereof.

The storage capacitor may be charged to a voltage level depending on thepresent or predicted load requirements. In one embodiment, a loadrequirement may be predicted by measuring or determining a current drawof the load and predicting the energy necessary to support the predictedload requirements.

In another embodiment, the load requirement may be predicted by takinginto account how the load behaved for a previously charged value. If,for instance, a prior prediction resulted in insufficient charge for theload, a storage capacitor charge may be increased. In this way, a chargeof a storage capacitor may take into account a history of charging thecapacitor to find an optimal predicted charge for the storage capacitor.As mentioned previously, in any embodiment any storage device orcombination of storage devices may alternatively and similarly be used.For instance, a storage inductor, super capacitor, battery, or any othersuitable storage device or combination of devices may be used andcharged in a similar fashion.

In one embodiment, a processor or other suitable circuitry may count thenumber of times over an observation interval that a voltage on thestorage capacitor is below a minimum threshold and when the countexceeds an error threshold, the system may change operating parametersto prevent future occasions of dropping below the minimum threshold.Further, the number of times corresponding to the error threshold andthe observation interval over which the number of times are counted maybe adjusted based on observed power conversion efficiency.

In another embodiment, the operating parameters may be adjustedimmediately after the count exceeds an error threshold without waitingfor the end of the observation interval. In another embodiment, thesystem may measure or determine the rate of discharge of the storagecapacitor and adjust the operating parameters based on the rate ofdischarge.

In another embodiment, the system may observe the rate of discharge ofenergy stored in the storage capacitor to determine operating parametersfor charging the storage capacitor. In another embodiment, the systemmay determine the rate of occasions at which the energy level in theenergy storage device drops below a minimum threshold. When the systemdetermines the rate of discharge of energy is lower than a thresholdrate or the rate of occasions when the energy level drops below aminimum threshold is too infrequent, the system may adjust the operatingparameters such that the storage capacitor may be charged lessfrequently or the system may suspend charging the storage capacitor foran extended period of time. In any embodiment, the system may determineor measure any other suitable indicator of a stored level of energy orrate of change of stored energy such as a voltage level, current level,power level, charge level, rate of change thereof, or any combinationthereof.

The power conversion system may calculate several efficiency factors. Anefficiency factor may be calculated by measuring the average actualpower delivered to the load divided by the average actual powerharvested from the input power source. Actual average input and outputpower are calculated by real-time measurements of actual real-timecurrents and voltages of the input and output. Different efficiencyfactors reflect averages over different durations of time. For example,the system may have three efficiency factors, calculated over 1 second,10 seconds, and 1 minute. The system may decide the relative importanceof the different efficiency factors depending on the operatingfactors/conditions.

During normal operation, the main controller may use the initialoperating parameters as initial values for controlling power conversion.The main controller may adjust each operating parameter according toreal-time reading or measuring of the factors/conditions. To determinehow to adjust each parameter, the main controller may either set theparameter to a value based on a known or expected effect of the adjustedvalue, or it may empirically determine an optimal value for eachoperating parameter by intentionally varying the value and recording theeffect. Through evaluating a history of the effect of adjustments to theoperating parameters, the main controller may determine an optimalsetting for each operating parameter associated with the presentoperating factors/conditions.

The main controller may adjust the operating parameters in a determinedorder. The determined order may be an order in which the operatingparameters may be evaluated and recalibrated based on the magnitude ofthe effect of their adjustment on real-time observed power conversionefficiency or their effect on any other operating factor/condition. Thedetermined order may also be based on or influenced by predefinedpreferences, preferred ordering, settings, user-selected inputs, loadinputs, default settings, initial weighting of positioning in order, orany combination thereof. In one embodiment, the system may prioritize orprefer the stabilization of one or more of the operatingfactors/conditions such as output voltage, power factor, harmonics, etc.During the adjustment process, the main controller observes and/orsamples the magnitude of the effects of the changes in the operatingparameters on the power conversion efficiency of the system. Once anoptimal setting is determined for a first operating parameter, the maincontroller may adjust the value of a second operating parameter andevaluate the magnitude of the effect of the change on power conversionefficiency.

If the magnitude of the effect of the change in the second operatingparameter is above a threshold magnitude, the main controller may returnto fine tune the value of the first operating parameter. The maincontroller may fine tune the value of the first operating parameter witha finer resolution than during the previous pass. The main controllermay then continue to the next operating parameter to fine tune the valueof the second operating parameter with a finer resolution than duringthe first pass. Such a process may continue in a loop fashion such thatthe main controller moves on to further operating parameter values oncea previous value generates an effect on an operating factor/condition,such as efficiency, that is below a magnitude threshold associated witha value that results in an acceptable value for the operatingfactor/condition.

Each time an adjustment of the value of an operating parameter causes aneffect having a magnitude which is beyond an acceptable threshold, themain controller may return to the first operating parameter and restartthe adjustment and evaluation process through another pass. The effectof the change in the operating parameters may or may not be an absolutecomparison of magnitudes. The comparison may be relative such that aneffect due to a change in one operating parameter may be weightedcompared to the effect of a change in another operating parameter. Thechange in an operating parameter may be weighted based on howsignificantly the change in the operating parameter affects the overallpower conversion efficiency. In this way, the system may determine anoptimal order in which to adjust operating parameters to arrive at anoptimal power conversion efficiency. The system may increase the speedat which it determines optimal operating parameters corresponding tooptimal power conversion efficiency by reordering the setting andadjusting of the operating parameters. In this way, the system may notjust obtain optimal operating parameters, but may optimize the method inwhich it arrives at the optimal operating parameters.

In another embodiment, if any of the factors/conditions of the systemchanges, the system may restart the aforementioned calibration process.Further, the system may periodically or sporadically recalibrate evenwhen changes in the factors/conditions of the system have not beenobserved. Further, a user or load device may override the order ofoperating parameter evaluation and adjustment and their values.

FIG. 5 includes a flow diagram depicting an exemplary process flow forone embodiment of the power conversion system. One should recognize thisis one of many ways in which the system may evaluate and adjustoperating parameters. The system may start at step 510 by determininginitial operating parameter values. The system may then move to step 515to set a sequence position to a first position. The system may then moveto step 520 to adjust an operating parameter at the sequence position.For the first time through the process flow, this may be the operatingparameter in the first position. The system may then move to step 525 todetermine whether the effect on operating factors/conditions are withinacceptable thresholds. If the magnitude of the effect is not acceptable,the system may return to step 520 to continue to adjust the operatingparameter until the effect is determined to be within an acceptablethreshold at step 525. The system may then move to step 530 to determineif the adjusted operating parameter is at an optimal value for targetoperating factor/condition values. If the adjusted operating parameteris not at an optimal value, the system may return to step 520 to adjustthe operating parameter to find an optimal position. If the operatingparameter is determined to be at an optimal value, the system may moveto step 535 to increment the sequence position, effectively moving tothe next operating parameter in the sequence. The next operatingparameter may then be adjusted at step 540 and evaluated in a similarfashion to the first operating parameter at step 545. If the effect ofthe adjustment on the next operating parameter is not within acceptablethresholds, the system may return to the first operating parameter toreadjust the first operating parameter. The system may continue to movethrough the parameters by returning to step 535 and moving on to step540 to adjust the operating parameter values until each operatingparameter adjustment causes an acceptable effect on the operatingfactors/conditions and the operating parameter values are determined tobe optimal at step 550. The evaluation concludes when the systemdetermines it has reached the end of the sequence at step 555 and theoperating parameters are considered to be set to optimal values at step560.

In another embodiment, the system may evaluate a first operatingfactor/condition based on the determined order and may decide whether toincrease or decrease one or more operating parameters based on otheroperating factors/conditions. Alternatively, the system may increase ordecrease the operating parameters without considering the otheroperating factors/conditions. Alternatively, the system may setoperating parameter values. For instance, the system may cause a switchto open or close earlier or later than previously planned or may open orclose a switch immediately and indefinitely. The system may immediatelyopen a switch without considering the effect on an operatingfactor/condition.

FIG. 6 includes a flow diagram depicting an exemplary process flow forone embodiment of the power conversion system for determining an orderof evaluation and adjustment of operating parameters. One shouldrecognize this is one of many ways in which the system may performsimilar operations. The system may begin at step 610 by moving to afirst operating parameter in a sequence and detecting an effect on avalue of a target operating factor/condition due to adjustments of anoperating parameter corresponding to the first position in the sequenceat step 615. The system may then move to a next operating parameter inthe sequence at step 620 and detect the effect on the value of thetarget operating factor/condition due to adjustments of the nextoperating parameter at step 625. At step 630, the system may thendetermine if the effect of adjustments of the next operating parameterare greater than the first operating parameter. If so, the system maymove to step 645 to swap the position of the operating parameters in thesequence and return to step 610 to evaluate the first operatingparameter in the sequence. In this way, the system may proceed throughthe sequence of operating parameters and rank them in a sequence suchthat the operating parameter with the greatest effect on a targetoperating factor/condition may be first and the operating parameter withthe least effect may be last. The system may determine at step 635 ifthe end of the sequence has been reached, and if so, the system mayconclude evaluation at step 640.

The system may prefer to adjust operating parameters in a particularorder based on one or more operating factors/conditions or may ignoreoperating factors/conditions. For instance, the system may prefer todecrease the value of an operating parameter first before increasing thevalue to search for and determine optimal performance settings. Theincreasing or decreasing of the operating parameter may cause a switchto open or close sooner or later than previously set. The preference forthe determined order of increasing or decreasing the values of theoperating parameters may change due to changing operatingfactors/conditions. The system may learn through a history of observedeffects of the change in operating parameters how to bias the preferredorder for increasing or decreasing the operating parameters. The systemmay further learn the preferred magnitude of change with which to adjustthe operating parameters. The system may also produce additionaloperating parameters. For instance, the system may decide to cause anadditional opening and closing of a switch or may decide to remove anopening and closing of a switch from operation. Alternatively, thenumber of times switches are opened and closed may be an operatingparameter and the system may appropriately adjust the number of timesthe switches chop the input. In this way, the system may take more orfewer portions from the input power.

In another embodiment, one or more operating factors/conditions maylimit the adjustment of an operating parameter. For instance, a firstoperating condition/factor may improve by increasing an operatingparameter, but a second operating condition/factor may trigger an eventwhich may limit or stop the system from increasing the operatingparameter. For example, the system may learn that the efficiencyincreases as it narrows the width of a portion of the input power.Therefore, the efficiency operating condition/factor would influence thesystem to narrow the portion. However, narrowing the portion may alsoincrease output ripple voltage. Once the magnitude of the output ripplevoltage exceeds a threshold, the system may limit the narrowing of theportion and hence limit the adjustment of the associated operatingparameters.

In another embodiment, the system may predict future operatingfactors/conditions based on current and past operatingfactors/conditions to responsively adjust operating parameters. Further,the system may adjust its preferred target operating factors/conditionsbased on observations, trends, and predictions. For instance, the systemmay observe that the power consumption of the load is higher thanexpected and recalibrate the target energy storage voltage valueoperating condition/factor in order to compensate for a predicted needfor additional energy in the energy storage. Therefore, the operatingparameters are adjusted appropriately to charge the energy storage withsufficient energy. Further, the system may further take into accountadditional operating factors/conditions when adjusting the operatingparameters. For instance, the system may take into account the positionof the planned portion along the input AC waveform to influence how thesystem repositions and/or resizes the portion to take energy from theinput waveform. For example, the system may shift the position of theplanned portion towards the peak of the AC waveform to harvestadditional energy from the input responsive to predicting elevated powerrequirements of the load.

In one embodiment, the system may adjust the operating parameters by aninitial step size corresponding to an initial resolution. The step sizemay be adjusted according to observed trends in the effect of the changein the operating parameters on the operating factors/conditions. Thesystem may adjust operating parameters with the chosen resolution whileobserving the effect of the change on the operating factors/conditions.The system may continue to change the operating parameters with thechosen resolution until the system observes or measures a degradation inone or more operating factors/conditions. The system may then readjustthe operating parameters using a smaller or larger step sizecorresponding to a finer or coarser resolution.

FIG. 7 includes a flow diagram depicting an exemplary process flow forone embodiment of the power conversion system for evaluating andadjusting operating parameters and determining a step size for adjustingthe operating parameters. One should recognize this is one of many waysin which the system may perform similar operations. The system may beginat step 710 by setting an adjustment direction to a first direction andsetting an initial step size at step 715. At step 720, the system maythen adjust an operating parameter in the first direction with theinitial step size. At step 725, the system may then determine if atarget operating factor/condition improved. For instance, the system mayevaluate whether an efficiency or output ripple level improved. If thetarget operating factor/condition improved, the system may continue tostep 730 to adjust the operating parameter in the same direction andevaluate the target operating factor/condition to determine if itdegraded at step 735. If at step 725, the system determines the targetoperating factor/condition did not improve, the system may move to step755 to reverse the adjustment direction and then move to step 730 toadjust the parameter. Once the system determines a degradation in thetarget operating factor/condition following an improvement at step 735,the system may then determine if the step size is small enough at 740.If the step size is determined to not be small enough at step 740, thesystem may move to step 760 to decrease a step size and then move tostep 755 to reverse the direction of adjustment. In this way, the systemmay use an iteratively increased resolution to determine an optimaloperating parameter setting for a target operating factor/condition. Ifthe system determines at step 740 that a fine enough resolution has beenused to adjust an operating parameter associated with a small enoughsize step, the system may move to step 745 to set the operatingparameter back to the previous value before the last adjustment. Thesystem may then move to step 750 to determine an optimal operatingparameter value has been found.

FIG. 8 includes a flow diagram depicting yet another exemplary processflow for an embodiment of the power conversion system. One shouldrecognize this is one of many ways in which the system may performsimilar operations. The process may begin at step 810 with a wake-up orrestart operation. The system may then read system settings at step 815.The system may then determine if a first run through parametercalibration is being performed at step 820. If the system determinesthis is a first run, the system may reset to factory settings at step895. If the system determines it is not a first run, the system may testanalog sensors and analog to digital converter (ADC) sensors as well astest the values for operating factors/conditions at step 825. At step830, the system may determine if an error or fault condition hasoccurred and if so, attempt to recover. If the recovery fails, thesystem may move to step 895 to reset to factory settings. If the systemdoes not recover from the error, the system may output an error messageat step 885 and stop at step 880. If no error or fault condition ispresent, the system may investigate a first operating parameter at step835 and may determine if an action is required at step 840 based on theinvestigation. If the system determines an action is required, thesystem may calibrate the operating parameter at step 845. If theefficiency has been increased by the calibration, the system may move tostep 870 to promote the operating parameter in the order of operatingparameters such that it may be adjusted earlier in the order ofoperating parameters. If efficiency has not increased, the system maymove to step 875 to investigate the next parameter in the order if thecurrent operating parameter is not the last parameter. The system maycontinue in a similar fashion to move through the remaining operatingparameters in the order and adjust operating parameters appropriatelywhile reordering parameters based on their effects on efficiency. Oncethe system has investigated all operating parameters in the order, thesystem may register the operating parameters at step 865 so that thesystem operates and controls switching in accordance with the updatedand calibrated operating parameters. The system may wait for a period oftime before restarting the evaluation of parameters.

FIG. 9 includes a flow diagram depicting yet another exemplary processflow for an embodiment of the power conversion system. One shouldrecognize this is one of many ways in which the system may performsimilar operations. The process may begin with a wake-up or restartoperation at step 910. The system may then read system settings at step915. The system may then determine at step 920 if a first run throughparameter calibration is being performed. If the system determines thisis a first run, the system may reset to factory settings at step 940. Ifthe system determines it is not a first run, the system may test analogsensors and analog to digital converter (ADC) sensors as well as testthe values for operating factors/conditions at step 925. The system maydetermine if an error or fault condition has occurred at step 930 and ifso, attempt to recover. If the recovery fails, the system may reset tofactory settings at step 940. If the system does not recover from theerror, the system may output an error message at step 950 and stop atstep 955. If no error or fault condition is present, the system may runa plurality of instances of a calibration procedures in parallel at step935.

The calibration procedure may start by freezing other processes at step960. The system may then mark an unmarked operating parameter andinvestigate the operating parameter at step 965. At step 970, if thesystem determines an action is required, the system may calibrate theoperating parameter at step 975. The system may determine if efficiencyhas been increased at step 980. If the efficiency has been increased bythe calibration, the system may promote the operating parameter in theorder of operating parameters at step 985 such that it may be adjustedearlier in the order of operating parameters. At step 990, the systemmay then register the operating parameter so that the system operatesand controls switching in accordance with the updated and calibratedoperating parameter. The system may wait for a period of time and/or maythen release the other frozen processes at step 995.

In one embodiment, the system may evaluate one or more operatingfactors/conditions and may decide how to set and adjust operatingparameters to chop the input. The system may evaluate one or moreoperating factors/conditions and may decide to chop the input into moreand narrower portions based on the result of the evaluation.Alternatively, the system may evaluate one or more operatingfactors/conditions and may decide to chop the input into fewer and widerportions. For example, the system may prefer to chop the input intofewer and wider portions to improve efficiency. Reducing the number oftimes switching occurs, the system may reduce power losses associatedwith switch driving and reduce accumulated in-rush currents when theinput voltage is near the peak of the AC waveform. However, the systemmay also be limited by other operating factors/conditions such as anacceptable level of harmonics. To limit harmonics, the system may preferto chop the input into more, narrower, back-to-back portions over thefull AC period. As such, the system may calibrate the operatingparameters taking into account both efficiency and harmonics to findoptimal operating parameters.

In another embodiment, the system may prefer to take portions of theinput waveform positioned along the waveform at voltages slightly abovethe energy storage voltage rather than near the peak voltage of theinput to improve power conversion efficiency. The preferred portions maystart and end at voltages slightly above the energy storage voltage. Theload may also demand energy at a rate such that the system may takeother portions to supplement the supply of energy to the energy storagedevice. Further, the system may take other portions when takingharmonics or other operating factors/conditions into consideration.

FIG. 10 depicts an example of chopping an input AC waveform by the powerconversion system for conversion to an output power for a load. Vs maybe the real-time voltage of the input at which the system begins takingenergy from the input for a first portion and Ve may be the real-timevoltage of the input at which the system stops taking energy from theinput.

Vpeak may be the voltage peak of the AC input waveform. The system mayset operating parameters to process and convert energy from the highervoltage portion by a first set of circuitry. The higher voltage portionmay be taken from a region of the AC waveform which contains voltageshigh enough for generation of the output voltage while being sufficientfor maintaining operating factors/conditions such as power factorcorrection, output ripple, etc. within acceptable thresholds. FIG. 10depicts the system taking portions of non-rectified AC input, however,the system may also rectify the input. In one embodiment, the system mayfull-wave rectify the AC input waveform before selecting portions of theinput. In another embodiment, the system may select portions of theinput and only rectify the selected portions.

FIG. 10 depicts a lower voltage portion which may be used by the systemfor power conversion. The lower voltage portion may be taken from aregion of the AC waveform that has voltages less than the desired outputvoltage. The lower voltage portion may be near the zero-crossing whichtakes place at t_(z). The system may set operating parameters to processand convert the energy from the lower voltage portion with a second setof circuitry which may amplify the voltage from the lower voltageportion to a sufficient voltage for conversion and delivery to theoutput.

In another embodiment, the system may provide reports on the calibrationhistory of the system. The system may provide reports on the history ofefficiency, the history of events, the history of operatingfactors/conditions, the history of fault events, etc. Alternatively,indicators or displays may be provided to indicate any of theaforementioned histories or events.

In one exemplary embodiment, if the system detects a disconnection ofthe load, the order and setting of the values of the various parametersmay be remembered for a period of time such that when the load isreconnected, the system may quickly arrive at near optimal operatingfactors/conditions without reordering the order of adjustment ofoperating parameters.

In another exemplary embodiment, if the system detects the load profilehas changed significantly due to, for instance, a laptop starting up ahard drive, the main controller may reorder the order of adjustment ofoperating parameters and/or may return to varying the value of theoperating parameters using a lower resolution.

In one embodiment, any operating condition/factor of the system maytrigger an event. An event may be triggered when an operatingcondition/factor crosses a threshold which may be static, dynamicallydetermined, user defined, or provided by the load. An operatingcondition/factor may have multiple thresholds associated with it.Responsive to an event, the system may decide to adjust operatingparameters. Alternatively, the system may decide to maintain the currentvalues of the operating parameters. Alternatively, the system may entera fault condition wherein the system may shut itself down for a periodof time or indefinitely, trigger an alert, transmit an error signal,transmit an error command/message, provide a visual error indicator,disconnect power to the load, disconnect itself from input power,require user intervention, automatically enter a recovery mode, or anycombination thereof. The system may alternatively ignore an event.

In another embodiment, the system may set operating parameters so thatswitching of the switched power converter chops the input into narrowportions such that the duration of the portion is short enough toprevent saturation of the energy storage device. For instance, thesystem may chop the input sufficiently narrowly so that a storagecapacitor is charged to a voltage less than the voltage of the inputportion. For example, the system may take a portion of the input of100V. The portion is narrow enough such that the energy it contains canonly charge the storage capacitor to a voltage less than 100V.

Two examples of this concept are illustrated in FIG. 12. FIG. 12 showsplots of voltage vs. time for two examples of a portion delivered to acapacitors serving as an energy storage device, and the voltage of thecapacitor. In both cases illustrated in FIG. 12, a portion of voltageVchop is delivered to a capacitor, wherein the capacitor is charged to avoltage Vcharged which is less than Vchop wherein the capacitor is alsonot charged to a saturated level. The portion is narrow enough such thatit stops charging the capacitor to a voltage less than Vchop and lessthan saturation. The capacitor's voltage is shown by Vcap as it ischarging. As seen in both examples in FIG. 12, the portion ends beforethe capacitor voltage can charge up to the full voltage of Vchop.Furthermore, in both cases shown in FIG. 12, the capacitors may not becharged to saturation.

In yet another embodiment, the system may comprise several energystorage devices. The system may chop the input into narrow portions anddirect the portions into one or more of the energy storage devices. Theenergy storage devices may be charged to a level less than or equal tothe present input voltage. FIG. 12 illustrates two examples of this. Bycharging the storage devices to lower voltages, ½CV² losses associatedwith charging the devices may be reduced compared to using a singleenergy storage device charged to the full input voltage. The system mayspread out the discharging of the energy storage devices over time suchthat accumulated i²r losses associated with discharging the devices maybe reduced. The system may spread out the discharging of the energystorage devices over time by sequentially discharging the energy storagedevices.

In an exemplary embodiment, the system may include intermediate chargingof capacitors wherein each intermediate capacitor is charged to afraction of the input voltage or the voltage of the portion delivered tothe capacitor. For instance, for n intermediate capacitors, eachintermediate capacitor may be charged to Vin/n volts. Switches maydischarge the intermediate capacitors to the energy storage device or tothe load in accordance with the requirements of the load. Theintermediate capacitors may be discharged simultaneously, alternating,in series with each other or in parallel with each other, or anycombination of the aforementioned. The intermediate capacitors may bedischarged to the storage capacitor, to the load, or may retain chargedepending on the present demands or predicted demands of the storagecapacitor or load.

In yet another embodiment, the system may include an additional energystorage component which may be used to reduce output ripple. Forexample, when the output ripple is close to or beyond an acceptablethreshold, the additional energy storage component may be used tocompensate the charging of the main energy storage capacitor. When theinput voltage is near a zero-crossing, the input may not be able toprovide sufficient energy to charge the energy storage capacitor. Thesystem may then set operating parameters to cause the additional energystorage component to deliver energy to the main energy storage capacitorto compensate for the lack of energy from the input. The additionalenergy storage component may be recharged and discharged into the mainenergy storage capacitor when needed.

FIG. 11 depicts an exemplary embodiment of a power conversion system inaccordance with the teachings above. While FIG. 11 shows the system witha particular number and configuration of switches, one skilled in theart should recognize the system may be implemented with fewer oradditional switches. Furthermore, though the switches are depicted astransistors, one or more of the switches may be implemented with diodes,mechanical switches, or any other suitable electrical mechanism suitablefor performing switching. One skilled in the art should also recognizethat though FIG. 11 depicts capacitors, any suitable storage devices orcombination of storage devices may be used. Furthermore, FIG. 11 depicts2 capacitors, C1 and C2, in addition to storage capacitor C3, howeverany number of capacitors may be used. FIG. 11 further depicts a 1 kresistor which is meant only as an exemplary load. Any load may besubstituted in place of the 1 k resistor. FIG. 11 further depicts a 50Hz AC input power source, however an AC input power source, DC inputpower source, or any combination thereof, may be used.

As detailed above, the system may set operating parameters to controlthe switching of the switches depicted in FIG. 11 to take appropriateportions of the input while controlling the stored energy in capacitorsC1, C2, and C3. In the system depicted in FIG. 11, switches S1, S2, S1′,and S2′ may be switched to function as a rectifying diode bridge.Switches S1, S2, S1′ and S2′ may be controlled by sensing zero-crossingsof the input and setting operating parameters to open and close theswitches appropriately to rectify the input. Furthermore, switches S1,S2, S1′, and S2′ may be controlled based on the capacitance values ofC1, C2, and C3 and may further be controlled based on the energy storedin the capacitors. Alternately, if a diode bridge were used, switch S3may be used and switched accordingly. Furthermore, the combination ofthe switches S1, S2, S1′, and S2′ may be controlled in a manner that mayeliminate a need for S3. Switch S4 may allow a charge supplied from thesource, and limited by switch S3 or the combination of switches S1 andS2, to be split between capacitors C1 and C2. In accordance with theteachings above, each of capacitors C1 and C2 may then be charged to avoltage that is less than the supplied voltage. In this case, capacitorsC1 and C2 may split the supplied voltage evenly, such that half thesupplied voltage is seen across each capacitor. As such, ½ CV² lossesmay be ¼ of those that would be seen by charging to the full voltage.Switches S5-S8 may be switched appropriately to charge the energystorage capacitor C3 when needed. The capacitors C1 and C2 may be usedas a charge source to top up the energy storage capacitor C3. SwitchesS5-S8 may be switched so that capacitors C1 and C2 are sequentiallydischarged into capacitor C3 to reduce i²r losses. While an inputvoltage is low, the switches may be controlled so that charge from theinput is transferred directly to C3 without first charging capacitors C1and C2.

In yet another embodiment, the system may set operating parameters tocompensate for a value of a circuit component or to adjust a value of acircuit component. For instance, switches may exist in the system whichmay couple in an additional capacitor in parallel with another capacitorto increase the total effective capacitance seen between the two nodesof the capacitor. The system may connect any number of additionalcapacitors to adjust an effective capacitance value. In a similarfashion, the system may connect in, for example, additional resistors,capacitors, inductors, and transistors to effectively change the valuesof other components in the system. Any other circuit components may beconnected through switches of any sort or any other mechanism to alteror compensate for the value of other components. In another embodiment,the system may include an LLC converter. Operating parameters may be setto connect additional components into the circuit to adjust a resonantfrequency of the LLC converter.

In yet another embodiment, the system may increase a number of channelsthrough which a load is powered or through which an energy storagedevice is charged to decrease losses and effectively increaseefficiency. The system may determine for a particular load demand toincrease the number of channels and hence increase the amount of metalthrough which the current from the system travels to reduce a traceresistance which may reduce losses associated with the trace resistance.

In yet another embodiment, a system may include an LLC converter. Thesystem may sample a self resonance of the LLC converter by sending oneor more pulses to the coils of the LLC converter. The pulses may beshort and the coils may not be loaded. The coils may be grounded duringthe sampling. The system may measure the time it takes for energy fromthe pulse to return and through this measurement determine the resonantfrequency. The LLC converter has a resonance, and hence a pulse injectedinto the LLC converter may return periodically, with decreasing energyeach subsequent period, at a rate of the resonant frequency. The systemmay determine the resonant frequency based on the observed rate of thereturned, periodic pulses.

In yet another embodiment, a system may sense the temperature of thecoils of an LLC converter and may change operating parameters based onthe sensed temperature or a change in the temperature. A change in thetemperature of the coils of an LLC converter may cause a change in theresonant frequency of the LLC converter. The system may seek to delivervoltage portions harvested from the input and may deliver them to theLLC converter at a frequency of the resonant frequency. In this way, thesystem may seek to synchronize timing of chopping of the input anddelivery of the input portions to the LLC converter.

In yet another embodiment, a system may sense/measure a power draw of aload and sense the temperature of the LLC converter. The system maycompare a change of a power draw of a load to a change in thetemperature of the LLC converter. The system may determine for ameasured change in the draw of the load an appropriate change in thetemperature of the LLC converter. If the system determines a differenttemperature change should have occurred for a measured change in thedraw of the load, the system may determine portions are not beingdelivered to the LLC converter optimally, possibly due to a changed LLCresonant frequency, and may adjust operating parameters to compensatehow the input portions are harvested and delivered to the LLC converter.As detailed previously, the system may adjust operating parameters byempirically observing whether the adjustment improves or degrades theefficiency of the system. Based on the empirical observations, thesystem may adjust the operating parameters to adjust the frequency ofthe portions to determine the most efficient frequency to mate with theresonant frequency of the LLC converter. For example, an LLC convertermay have a nominal resonant frequency of 120 kHz, however temperaturefluctuations and a change in load power draw may cause this resonantfrequency to change. The system may adjust operating parameters tocompensate for this change.

In yet another embodiment, the system may compare an observed result ofdelivering a portion to the LLC converter to an expected result. Thesystem may determine when the observed result is not the same as theexpected result that operating conditions may have changed and thesystem may adjust operating parameters to compensate. In one example,fluctuations in the magnetic field of the coils of the LLC converter mayoccur. The system may observed these disturbances through measurementsof currents and voltages and adjust operating parameters to compensate.In one example, the system may adjust the timing of the input portionsbeing delivered to the LLC converter, the frequency of the inputportions being delivered to the LLC converter, or both, to compensatefor non-ideal observed operating conditions. In this way, the system mayattempt to optimize efficiency while the system experiences non-idealdisturbances by compensating for the disturbances. The system may adjustoperating parameters to synchronize with the timing of the resonance ofthe energy in the LLC converter to increase efficiency.

In yet another embodiment, the system may prefer to take wider portionsfrom regions of an input AC waveform in the voltage ranges of the ACwaveform near the zero crossings, and may prefer to take narrowerportions from regions of the input AC waveform in the voltage ranges ofthe AC wave form near the peak of the AC waveform. The system may varythe width of the portions to harvest sufficient energy to charge acapacitor without harvesting more than necessary to charge thecapacitor. By taking wider and narrower portions, the system may bedeviating from the resonant frequency of the LLC converter which mayresult in less than optimal efficient. As such, the system may adjustoperating parameters to seek to harvest portions with an averagefrequency that synchronizes with the resonant frequency of the LLCconverter.

In yet another embodiment, a system may use a capacitor to delay thedelivery of the voltage of an input portion to the coils of the LLCconverter. The system may set operating parameters to adjust the numberof capacitors, and hence the effective capacitance, used to delay thevoltage of an input portion. In this way, the system may compensate forportions being taken at frequencies that diverge from the resonantfrequency of the LLC converter and synchronize the delivery of theportions to the resonance of the LLC converter.

In yet another embodiment, a system may set operating parameters toadjust the voltage level that is delivered to the coils to synchronizepower transfer with the resonance of the coils. The system may adjust avoltage level on a storage capacitor or adjust a gain or amplificationto adjust the voltage level that is delivered to the coils. Also, byincreasing/amplifying the voltage of an input portion, the system mayreduce the overall effect of diode-drop type losses associated withtransistors used in the path which may increase efficiency.

In yet another embodiment, a system may set operating parameters toaccumulate a plurality of portions before delivery them to the LLCconverter. The system may accumulate energy from multiple portions toimprove synchronization with the resonance of the LLC converter. Thesystem may set operating parameters to collect portions, wait a periodof time before collecting a portion, or stop collecting portions toimprove the synchronization of the delivery of the portions with theresonances of the LLC. The system may skip harvesting a portion from theinput because a capacitor intended to store the energy of the portion isfully charged. The system may also immediately stop harvesting a portionfrom the input so that it may be immediately delivered to the LLCconverter to improve synchronization with the resonances of the LLCconverter. In this way, the system configured to set operatingparameters to flexibly adjust the timing of the chopping of the inputand the delivery of the portions to the LLC converter to synchronizewith the resonance of the LLC converter which may improve the overallefficiency of the system.

In yet another embodiment, the system may detect it has beendisconnected from an input power and may set operating parameters toallow a draining resistance to discharge energy across the drainingresistance. The system may implement the draining resistance in afail-safe mode wherein the system may actively keep the resistance as anopen so that it does not dissipate power while the system is connectedto an input power, but closes across line and neutral to dischargeenergy when the system is disconnected from power. FIG. 2 illustrates anexample of control signals being received by the EMI filter and inputprotection stage. Such control signals may control the state of thedraining resistance and may effectively keep the draining resistanceopen while connected to input power.

In yet another embodiment, the system may set operating parameters toadjust a number of EMI filters applied to the input of the system basedon a measured load. For lower load draws, for instance under 70 watts,the system may only connect one EMI filter. For higher load draws, forinstance over 70 watts, the system may connect a plurality of EMIfilters. FIG. 2 illustrates an example of control signals being receivedby the EMI filter and input protection stage. Such control signals maycontrol the number of EMI filters connected. By connecting only thenecessary number of EMI filters for a given load, the system may reducelosses that may have been introduced by the extra EMI filters andthereby improve efficiency.

The aforementioned embodiments provide a wealth of solutions forflexibly and efficiently converting an input power into an output power.Although the embodiments describe exemplary arrangements andcombinations of features, a system in accordance with the teachingsherein may incorporate any combination of the described features,capabilities, and configurations. One of ordinary skill in the art willappreciate that each embodiment, feature, or element can be used aloneor in any combination with the other embodiments, features, andelements. In addition, the methods described herein may be implementedin a computer program, software, or firmware incorporated in acomputer-readable medium for execution by a computer or processor.Examples of computer-readable media include electronic signals(transmitted over wired or wireless connections) and computer-readablestorage media. Examples of computer-readable storage media include, butare not limited to, a read only memory (ROM), a random access memory(RAM), a register, cache memory, semiconductor memory devices, magneticmedia such as internal hard disks and removable disks, magneto-opticalmedia, and optical media such as CD-ROM disks, and digital versatiledisks (DVDs). A processor in association with software may be used toimplement an AC to DC power converter, DC to DC power converter, powersupply, voltage/current supply, energy storage, or any other form ofelectrical converter.

What is claimed is:
 1. A power converter comprising: an input configuredto receive an alternating current (AC) input power waveform from aninput power source; a switched power converter configured to: harvestpower from one or more portions of a first half-wave of the AC inputpower waveform; and harvest power from one or more portions of a secondhalf-wave of the AC input power waveform; wherein at least one locationof at least one of the one or more portions of the first half-wave isdifferent than at least one location of at least one of the one or moreportions of the second half-wave; and an output stage configured to:receive the harvested power; and convert the harvested power into aconverted power.
 2. The power converter of claim 1, further comprising:an energy storage device configured to store the converted power.
 3. Thepower converter of claim 1, further comprising: a processing moduleconfigured to: select the locations of the one or more portions of thefirst half-wave; select the locations of the one or more portions of thesecond half-wave; and send control signals to the switched powerconverter based on the selected locations of the one or more portions ofthe first half-wave and based on the selected locations of the one ormore portions of the second half-wave.
 4. The power converter of claim3, wherein the processing module is further configured to: determine oneor more settings for the output stage; and send one or more controlsignals to the output stage based on the determined one or moresettings.
 5. The power converter of claim 3, wherein each of thelocations of the portions includes a position and a width, and whereinthe processing module is further configured to: select a width of aportion of the first half-wave; and select a width of a portion of thesecond half-wave, such that the width of the portion of the secondhalf-wave is wider than the width of the portion of the first half-wave.6. The power converter of claim 3, wherein the processing module isfurther configured to: select a different number of portions of thefirst half-wave than number of portions of the second half-wave.
 7. Thepower converter of claim 3, wherein the processing module is furtherconfigured to: select a location of a first portion of the one or moreportions of the first half-wave; and select a location of a secondportion of the one or more portions of the first half-wave; wherein thelocations of the first portion and the second portion are such that agap exists between the first portion and the second portion in which noother portion exists.
 8. The power converter of claim 7, wherein theprocessing module is further configured to: adjust the locations of thefirst portion and the second portion such that corresponding portions ofthe second half-wave are a different distance apart than in the firsthalf-wave.
 9. The power converter of claim 7, wherein the processingmodule is further configured to: adjust a width of a first portion ofthe one or more portions of the first half-wave such that a width of acorresponding portion of the second half-wave is different than in thefirst half-wave.
 10. The power converter of claim 1, wherein theswitched power converter is further configured to: harvest power from aplurality of consecutive half-waves of the AC input power waveform suchthat different portions of the power are harvested from each half-waveof the plurality of consecutive half-waves of the AC input powerwaveform.
 11. A method for converting power in a power converter, themethod comprising: receiving an alternating current (AC) input powerwaveform from an input power source; harvesting power from one or moreportions of a first half-wave of the AC input power waveform; harvestingpower from one or more portions of a second half-wave of the AC inputpower waveform; and converting the harvested power into a convertedpower; wherein at least one location of at least one of the one or moreportions of the first half-wave is different than at least one locationof at least one of the one or more portions of the second half-wave. 12.The method of claim 11, further comprising: storing the converted powerin an energy storage device.
 13. The method of claim 11, furthercomprising: selecting the locations of the one or more portions of thefirst half-wave; selecting the locations of the one or more portions ofthe second half-wave; and sending control signals to control theharvesting based on the selected locations of the one or more portionsof the first half-wave and based on the selected locations of the one ormore portions of the second half-wave.
 14. The method of claim 13,further comprising: determining one or more settings for an outputstage; and sending one or more control signals to the output stage basedon the determined one or more settings.
 15. The method of claim 13,wherein each of the locations of the portions includes a position and awidth, the method further comprising: selecting a width of a portion ofthe first half-wave; and selecting a width of a portion of the secondhalf-wave, such that the width of the portion of the second half-wave iswider than the width of the portion of the first half-wave.
 16. Themethod of claim 13, further comprising: selecting a different number ofportions of the first half-wave than number of portions of the secondhalf-wave.
 17. The method of claim 13, further comprising: selecting alocation of a first portion of the one or more portions of the firsthalf-wave; and selecting a location of a second portion of the one ormore portions of the first half-wave; wherein the locations of the firstportion and the second portion are such that a gap exists between thefirst portion and the second portion in which no other portion exists.18. The method of claim 17, further comprising: adjusting the locationsof the first portion and the second portion such that correspondingportions of the second half-wave are a different distance apart than inthe first half-wave.
 19. The method of claim 17, further comprising:adjusting a width of a first portion of the one or more portions of thefirst half-wave such that a width of a corresponding portion of thesecond half-wave is different than in the first half-wave.
 20. Themethod of claim 11, further comprising: harvesting power from aplurality of consecutive half-waves of the AC input power waveform suchthat different portions of the power are harvested from each half-waveof the plurality of consecutive half-waves of the AC input powerwaveform.